In this post in the Bill & Melinda Gates Foundation’s “Impatient Optimists” blog, Jose Esparza, deputy director of vaccines and HIV at the Gates Foundation, reports on AIDS Vaccine 2011, a conference being held this week in Bangkok, Thailand, that is expected to draw more than 800 scientists and policymakers from around the world. He writes, “I’ve never been more optimistic about the prospect for developing a safe, effective and accessible vaccine to prevent AIDS,” based on recent developments expected to be presented at the conference (9/13).